1. Field of the Invention
The present invention relates to a secondary battery, and more particularly, to a secondary battery that can simplify a manufacturing process for an assembly of a bare cell and a protection circuit module, and reduce manufacturing costs.
2. Description of the Related Art
Generally, as lightweight and high-function portable wireless devices, such as video cameras, cellular phones, portable computers, and others, have been developed, a lot of research on the secondary battery which are used as a driving power supply of the portable wireless device has been performed. For example, the secondary batteries include nickel-cadmium batteries, nickel-hydrogen batteries, a nickel-zinc battery and lithium secondary batteries, etc. Among them, the lithium secondary battery is widely used for an electronic appliance field because the lithium secondary battery can be recharged and the size can be miniaturized, and the lithium secondary battery has a high capacity, a high operating voltage and a high energy density per unit weight.
The lithium secondary battery is formed by mounting a safety device, such as a PTC (positive temperature coefficient) element, a thermal fuse and a protection circuit module, on an electrode assembly including a cathode, an anode and a separator. A can receives the electrode assembly and an electrolyte, and a bare cell seals an upper end opening of a can by a cap assembly, and is received in a separate packing case, or filled with hot melt resin, tubed and labeled by a thin packing material. The safety devices prevent fire or explosion by shutting down an electric current, when an interior temperature of the battery becomes too high by connecting a cathode terminal of the bare cell to an anode terminal by a lead plate of a conducting material, or when a voltage is increased by overcharge, or when some other operational characteristic of the battery deviates excessively from its normal range of operation.
A conventional battery pack may be constructed with a bare cell having an electrode terminal protruding toward one short side edge surface so as to be charged and discharged, a core pack including a protection circuit module combined with one side surface of the bare cell. A resin molded part may be formed so as to be installed on an outer set while the protection circuit module preventing from separating from the bare cell by a hot melt technique of filling hot-melt resin on an upper region of the core pack including the protection circuit module, and an outer cover covering both side parts of the core pack to form a part of the outer appearance.
Conventionally, when the core pack of the lithium secondary battery was manufactured, the lead plate was included on both side surfaces of the protection circuit module so that the bare cell was coupled to the protection circuit module. The conventional lithium secondary battery includes two lead plates extending in a different direction about the protection circuit module, and a separate outer cover that covers the lead plates so that a manufacturing process of the battery pack is finished. Accordingly, manufacturing cost of a whole battery is increased by each of these features, and the number of manufacturing steps is also concomitantly increased.
The outer cover was respectively arranged in both right and left directions of the battery. Therefore, a degree of freedom of a design according to the miniaturization of the battery was limited because width of the battery became longer.